1993 LT1 WOT Ignition Timing

X-Vette · 12-14-2004, 05:47 PM

About 1 1/2 years ago I modified my 1993 LT1 engine from 350 cid to 383. I had a chip burned for this conversion and I have to say the car ran exceptionally well. After a little more than a year I blew a head gasket and a piston. I have recently rebuilt the engine, and I plan to dyno the engine to get better data to re-burn a new chip. My concern is using the first chip as it seems to have a very high amount of advance at wide open throttle and I don't want to get any detonation during any on-road data collection or dyno testing.

My question is as follows: Does anyone know what the factory calibration spark curve is for a 1993 LT1 at WOT or 95-100 kpa?

What I have now seems very high, but I'm not sure how it compares to an OEM curve. Following is the data on my modified chip at 95-100 kpa that I am currently using:

2200 rpm (35*), 2400 rpm (36*), 2800 rpm (38*), 3200 rpm (38*), 3600 rpm (39*), 4000 rpm (39*), 4500 rpm (39*), 5000 and up rpm (41*)

I would like to compare the two curves to see if there is any similarity or if I am way out of line. Some data I've seen on newer corvettes suggests much lower numbers and a curve that has a 5* drop after reaching maximum torque.

I am trying to get a little more informed before I press my engine.... rebuilds are not nice.

Thanks for any help.

X-Vette (I've rebodied my Corvette with a new carbon fiber body of my own design)

93Blackrose · 12-14-2004, 10:47 PM

The factory 93 timing tables at 95 and 100 kpa are

95 100
2000 - 30* 30*
2200 - 31* 30*
2400 - 32* 31*
2800 - 34* 33*
3200 - 34* 34*
3600 - 35* 34*
4000 - 35* 34*
4500 - 36* 35*
5000 - 37* 37*
5500 - 38* 38*
6000 - 38* 38*
6500 - 37* 37*

I think 41* maybe a little too much timing for a 383. You may want to drop it to 36* and get it to a dyno and tune from 36*

REDC4CORVETTE · 12-16-2004, 06:48 AM

My 94 reads 39 to 40 at 5800 rps but its a diff computer.
Reading with tts system.

X-Vette · 12-16-2004, 09:40 PM

93Blackrose

Thanks for your reply. I am obviously running too much of a spark advance. I will have a new chip burnt with the lower number to be on the safe side and work up from there on a dyno.

X-Vette

Quote:

Originally Posted by 93Blackrose

The factory 93 timing tables at 95 and 100 kpa are

95 100
2000 - 30* 30*
2200 - 31* 30*
2400 - 32* 31*
2800 - 34* 33*
3200 - 34* 34*
3600 - 35* 34*
4000 - 35* 34*
4500 - 36* 35*
5000 - 37* 37*
5500 - 38* 38*
6000 - 38* 38*
6500 - 37* 37*

I think 41* maybe a little too much timing for a 383. You may want to drop it to 36* and get it to a dyno and tune from 36*